Leadless atrioventricular synchronous pacing in an outpatient setting: Early lessons learned on factors affecting atrioventricular synchrony.

Background: Leadless pacemakers (PMs) capable of atrioventricular (AV) synchronous pacing have recently been introduced. Initial feasibility studies were promising but limited to just a few minutes of AV synchronous pacing. Real-world, long-term data on AV synchrony and programming adjustments affecting AV synchrony in outpatients are lacking.
Objective: The purpose of this study was to investigate AV synchrony and influences of PM programming adjustments in outpatients with leadless VDD PMs.
Methods: All patients who received a leadless VDD PM (Micra™ AV, Medtronic) between July 2020 and May 2021 at our center were included in this observational study. AV synchrony was assessed repeatedly postoperatively and during follow-up using Holter electrocardiographic (ECG) recordings. AV synchrony was defined as a QRS complex preceded by a p wave within 300 ms. The impact of programming changes during follow-up on AV synchrony was studied.
Results: A total of 816 hours of Holter ECG from 20 outpatients were analyzed. During predominantly paced episodes (≥80% ventricular pacing), median AV synchrony was 91% [interquartile range (IQR) 34%-100%] when patients had sinus rates 50-80/min. Median AV synchrony was lower when patients had sinus rates >80/min [33% (29%-46%); P <.001]. During a stepwise optimization protocol, AV synchrony could be improved (P <.038). Multivariate analysis showed that a shorter maximum A3 window end (P <.001), lower A3 threshold (P = .046), and minimum A4 threshold (P <.001) improved AV synchrony.
Conclusion: Successful VDD pacing in the outpatient setting during higher sinus rates is more difficult to achieve than can be presumed based on initial feasibility studies. The devices often require multiple reprogramming to maximize AV sequential pacing.
(Copyright © 2021 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)